CHAPTER 5: INTRO TO NATURAL HAZARDS5.1 HAZARDS, DISASTERS AND NATURAL PROCESSESNatural Disasters: Loss of Life and Property Damages- Examples: hurricanes, floods, earthquakes- Kill and average of 150,000 people annually worldwide- *These catastrophes (terrible disasters) were caused by natural hazards, but their effects were affected by human population density and land use pattersWhy Natural Processes are Sometimes Hazardous- Become hazardous when people live or work in areas where natural hazards occur- Or when land use changes like urbanization or deforestation affect natural processes- It is the geologists role to identify potentially hazardous processes, but it is difficult to get people to follow geologists advice and warningsMagnitude and Frequency- In general frequency is inversely related to the magnitude of disastrous eventso Ex- small earthquakes occur more often than large ones- But may be influenced by factors like climate and land useBenefits of natural Hazards- Flooding- provides fertile soil for farming and flushes pollutants from estuaries- Volcanoes- create new land (Hawaiian islands), and ash may fertilize soil for wild plants- Earthquakes- may create a fault gouge-clay zone along fault that provides a natural subsurface for dams and water resources (ex- San Andreas Fault oases)o Also important in mountain building = beautiful US scenic resources!Death and Damage caused by Natural Resources- Great loss of life does not always correlate with extensive property damage- In US, largest numbers of death is caused by tornadoes and wind storms - Los of life from earthquakes varies from year to year- Expansive soil cause over $3billion in damages annually- Catastrophe- any situation in which damages to people, property or society are sufficient such that recovery or rehabilitation is a long involved process - Effects of natural hazards change with time- Damages from hazards in the US is increasing, but death is decreasing due to better forecasting and warning5.2 EVALUATING HAZARDS: HISTORY, LINKAGES, DISASTR PREDICTIN AND RISK ASSESMENTFundamental Principles Concerning Natural Hazards- 5 principles to understand and minimize impact of natural hazards1. Hazards are known from Scientific Evaluation- identified using scientific method and monitored for future activity by using past events2. Risk analyses is an important component in understanding impacts resulting from hazardous processes-based on the probability of the event occurring and consequences resulting from the event3. Hazards are linked- ex- earthquakes can produce landslides and tsunamis4. Hazardous events that previously produced disasters are often now producing catastrophes- increasing human population and land usage is making disasters into catastrophes5. Consequences of hazards ca be minimized- through scientific understanding, land use planning, and proactive disaster preparednessRole of History In Understanding Hazards- Hazardous events are repetitive, and studying history provides information for hazard reduction plans- We can study geologic environment from prehistoric eventso Hydrologists use to study stream flow - Integrating historical information wit present conditions provides the “big Picture” and a better understanding of a possible future hazard and its possible effectsLinkage between Hazardous Events- Hazards are linked- earthquakes may cause a tsunami- Earth’s material is linked to hazards- shale is composed of loosely compacted tiny sediments prone to landslidesDisaster forecast, Prediction and Warning- Prediction- specifying date, time and size of event versus Forecast- ranges in certaintyo These help minimize los of life and damageo To predict and forecast we must: Identify the location where the event will likely occur- from past events , ex- have landslides on steep slopes where expansive soils exist Determine the probability of an event of a given magnitude- drought due to lack of rainfall Observe precursor events-land may creep before a landslide **then the event can be forecasted or predicted and the public can be warnedo Warning- from regional officials to local officials and then to the publicRisk Assessment- Risk Determination -Risk- product of probability that an event will occur multiplied by the consequences should it occur- Acceptable Risk- risk an individual is willing to endure- Problems and opportunities for Risk Assessment- it is difficult to determine consequences of an event or series of eventso Information is often complicated and difficult to analyzeo However, our ability to predict hazardous events and estimate their consequences are improving5.3 HUMAN RESPONSE TO HAZARDSReactive Response: Impact of and Recovery from Disaster- Direct effects- people killed, injured, displaced, or damaged from a particular event- Indirect effect- responses to disaster such as emotional distress, donation of money and taxes to finance recovery- Take time to plan future developments to avoid possible hazardous problems, from previous hazardous evento Ex- don’t build homes on floodplains or restructure buildings for earthquakesAnticipatory response: Perceiving, Avoiding, and Adjusting to Hazard- Perceiving- Hazard reduction programs depend on attitudes of people likely to be affected by hazardo People don’t always take hazards like floods and forest fires seriously becausethey do not happen frequently- Avoid- ex-CA local regulations stipulate that homes must be roofed with shingles that don’t burn readily- Adjust- land use planning – one of the most environmental sound adjustmentso Ex- don’t build houses on floodplains- Insurance, evacuation and disaster preparedness(training individuals or institutionson how to evacuate or treat large amounts of injured people) are ways to deal with natural hazardsArtificial control of Natural Processes- Mixed success- Ex- seawall to control coastal erosion, channels and dams for flood control5.4 GLOBAL CLIMATE AND HAZARDS- Global and regional climate change may affect the incidence of hazardous natural events like landslides, droughts and fires- Ex-Global Warmino Sea level rise as glacial melts and warming ocean wate expands Increase costal erosiono Food production areas will shifto Northern latitudes could become more productiveo Could cause global population shifts**o Warming atmosphere also could increase frequency and severity of hazardous